The processing procedures for making shaped rice products are set forth in U.S. Pat. No. 3,711,295. Many of the special physical properties of shaped rice products such as light-density texture, dryness, flavor, freeze/thaw stability, and firmness are the result of the characteristics of the rice from which it is made. It was first determined which special physical properties were to be incorporated into the finished product. It was then necessary to purchase and use the particular varieties of rice that would produce these properties.
This selection of particular varieties of rice had to be followed because the various properties of raw rice are so different. These rice properties include rice flavor, individual cooking time and temperature, freeze/thaw resistance, and textural qualities such as rubberiness, pastiness, dryness, stickiness, density, softness, and firmness. Even identical rice varieties grown within the same location have physical properties that vary. When the same rice varieties which are grown in different locations are compared, the variations in physical properties are even greater. Also, the properties of imported rice vary greatly from domestic rice. In addition, the aging of rice creates changes in rice properties. In fact, the properties of even the same batch of rice change from the time the rice is freshly harvested until it is entirely consumed the next year. Therefore, it was necessary to purchase and use only the particular varieties of properly aged rice that would give the desired properties in the finished product.
It is desirable to use domestic and/or foreign, off-color, broken-grain rice, or rice particles, because they are less expensive and produce a finished product which is as good as that produced with whole-grain rice. Until recently, one could easily purchase these rice by-products inexpensively and according to the variety of rice they originated from. At the present time, rice is more expensive because of a world shortage. As a result, identified whole-grain rice and off-grade rice can still be obtained but only at a premium price. The least expensive way to purchase rice by-products is in a bulk mixture of unidentified rice.
A knowledge of the rice variety and its age permits a fairly accurate prediction of its cooking conditions and finished product textural properties (i.e. softness, density, dryness, pastiness, and compactness). However, when a mixture of unidentified rice varieties is cooked together, part of the rice may become over-cooked and pasty while the remaining rice may be under-cooked and grainy. Even when only one variety of unknown rice is used, occasionally the proper cooking time and temperature is misjudged and the rice can either be over-cooked or under-cooked. Finally, even when only one variety of unknown rice is used, it may be of the type that produces poor textural properties even if properly cooked.